Electronic functional testing of electronic devices such as integrated circuits (ICs) or circuit assemblies is typically performed by automated testing systems. Generally, such automated testing systems interface with device handlers that convey the ICs or circuit assemblies to positions for testing.
In positioning an electronic device for testing, a test head of an automated testing system is connected to a test position associated with a device handler. The procedure of connecting to the test position is known in the art as docking. Docking requires an alignment of the test head to the test position and, thereafter, locking the test head to the device handler at the test position. Thus locked, a secured test position is obtained to thereby enable consistent and repeatable test results.
Generally, electronic devices that operate at high frequencies are tested with test signals of similar frequencies. Consequently, to alleviate undesired signals at these high frequencies, electronic test circuits of automated testing systems are ideally located as close as possible to the electronic devices. Hence, test heads for such automatic testing systems are densely packaged with these electronic test circuits in close proximity to the electronic devices that are to be tested.
Dense packing of electronic test circuits on a test head makes the test head bulky and heavy. Manipulating or positioning such a test head is not easy and, generally, an operator has to use a manipulating or positioning apparatus to align and then lock a test head to a test position. This can be a problem as any undesired movement, even in the millimeter range, can cause misalignment in the positioning of electronic devices. Such misalignment leads to incorrect or improper testing of the electronic devices or, in extreme situations, damage to the test head.
To overcome the delicate procedure of test head alignment, U.S. Pat. No. 6,271,658 B1 Vallinan et al., assigned to ST Assembly Test Services Pte. Ltd., describes a docking system having two plates, one attached to a device handler and the other to a device tester. Each of the two test plates has a substructure that allows for an easier initial alignment between the two plates and, thereafter, securely positioning and interlocking a handler plate with a test head. In another related prior art, U.S. Pat. No. 6,304,092 B1 Jordan, assigned to Credence Systems Corporation, describes two docking bars that enable a test head to dock with a wafer prober without requiring a calibration bar.
However, existing docking systems described, for example, in U.S. Pat. No. 6,271,658 and U.S. Pat. No. 6,304,092, are not designed to allow variations in the separation between the two plates without having to modify, for example, at least one of the two docking bars or one of the two test plates. Furthermore, elements or features of such existing docking systems do not enable the use of automated docking mechanisms. Consequently, human operators are still needed to manipulate or to position test heads in such existing docking systems. In addition, cable wires in the docking system described in U.S. Pat. No. 6,271,658 can be a problem as, over time, such cable wires slacken through use and, therefore, affect docking accuracy.
Therefore, a need clearly exists for a docking system that enables test heads of automated test systems from different test systems manufacturers to be connected to device handlers of different device handler manufacturers. Furthermore, the docking system should have features that enable the use of automated docking mechanisms to thereby alleviate the need for human operators.